Method and circuit for driving electrophoretic display, electrophoretic display and electronic device using same

ABSTRACT

A method for driving an active matrix electrophoretic display is provided. In a resetting period Tr, reset data Drest is supplied to a data line drive circuit and a reset voltage is applied to each pixel electrode. Next in a writing period, an image data is supplied to a data line drive circuit and a gradation voltage is applied to each pixel electrode. Subsequently a common voltage is applied to it, in order to take charge which is accumulated between the electrodes away, applying no electric field to a dispersal system. Then a displayed image is held.

This is a Division of application Ser. No. 09/884,092 filed Jun. 20,2001 now U.S. Pat. No. 6,762,744. The entire disclosure of the priorapplication is hereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates to an electrophoretic display, a methodand apparatus for driving it, and an electronic device using it.

2. Description of Related Art

In the conventional art, electrophoretic displays are known whichconsist of a pair of panels or substrates spaced apart in opposingrelation, each of which is provided with an electrode. Between theseelectrodes a dyed dielectric fluid is provided. Suspended in the fluidare electrically charged particles having a pigment color different tothe fluid in which they are suspended (hereinafter referred to simply aspigment particles). In a display update operation, differing voltagesare applied via a switching element to the electrodes to generate anelectrostatic field in the dielectric fluid, causing the pigmentparticles to migrate in the direction of the applied field.

Electrophoretic displays utilizing an electrophoresis phenomenon areclassed as non-luminous devices. In electrophoresis, pigment particlesmigrate under the action of Coulomb force which is generated when anelectrostatic field is applied to a dielectric fluid in which theparticles are dispersed.

However, prior art electrophoretic displays suffer from a problem inthat they afford poor viewing characteristics. The present invention hasbeen made to overcome this problem, and provides for the first time anactive matrix electrophoretic display, which display has superiorviewing characteristics.

SUMMARY OF THE INVENTION

As stated above, the object of the present invention is to provide anactive matrix electrophoretic display. Also provided is a drive circuitintegral to the device, and a method for driving the display by usingthe circuit. In addition there is provided is an electronic deviceattached to the electrophoretic display.

A method provided by the present invention is applied to anelectrophoretic display comprising a common electrode, a plurality ofpixels and a plurality of switching elements, each of which is assignedto a corresponding one of a plurality of switching elements. Each of thepixels is comprised of a pixel electrode which is connected to acorresponding switching element, with the pixel electrode being providedin spaced opposing relation to the common electrode, and a dispersalsystem comprising a colored fluid in which pigment particles aresuspended being provided between the common electrode and the pixelelectrode.

In the method of the present invention, a 1st voltage is applied to thecommon electrode. A 2nd voltage is then applied for a set period of timevia a corresponding switching element to a pixel electrode, to generatean electrostatic field in the dispersal system of the pixel, to causethe pigment particles to migrate in the direction of the thus generatedfield to a desired position, which corresponds to a desired colorgradation of the pixel. Next, the 1st voltage is applied via acorresponding switching element to the pixel electrode, to cancel theelectrostatic filed and fix said pigment particles in a desiredposition.

In the present invention, in addition to these steps, which are commonto the prior art, a new method is employed whereby differential voltagesare applied which are calculated on the basis of a difference between acurrent average position of pigment particles and a subsequent desiredposition. By continually updating the voltage gradient using theseparameters, positions of pigment particles can be updated without theneed for an initialization step. Since no initialization step isrequired, display updates can be affected rapidly.

In the present invention, to further improve display imagecharacteristics, it is preferable for there to be variations in theproperties of pigment particles employed, such as charge and mass. Asnoted above, in the present invention pigment particles do not need tobe initialized before a display update is made. This helps to overcome aproblem which conventional electrophoretic displays suffer from, wherebyafter a voltage differential between electrodes is cancelled, pigmentparticles continue to move under their inertia. This residual movementof pigment particles causes fluctuations in an image displayed. In thecase that minimal fluid resistance acts against pigment particles,inertial movement of the particles and resulting display fluctuationsbecome pronounced. To overcome this problem of inertial particlemovement, in the method of the present invention, after a differentialvoltage is applied to a second electrode, a further ‘brake’ voltage isapplied to the dielectric fluid to stop movement of the pigmentparticles rapidly. Since a direction of motion of a particle isdetermined by a direction and polarity of an applied electrostaticfield, a brake voltage to be applied has a polarity which is opposite tothat of a voltage applied to a pixel electrode. Different from prior artdisplays, in the electrophoretic display of the present invention aplurality of discrete dispersal systems are employed in electricalcommunication with a common electrode. The dispersal systems comprise acolored dielectric fluid in which contrasting pigment particles aresuspended; a plurality of data lines; a plurality of scanning lines; anda plurality of switching elements, which are provided at intersectionsbetween scanning and data lines. In addition, a plurality of pixelelectrodes is also provided, and each of these pixel electrodes isconnected to a corresponding switching element, and is also subject to acharge applied by the common electrode. In the method of driving thedisplay of the present invention, a voltage is applied to the commonelectrode, and scanning lines are then subjected to sequentialselection. In a next step, a voltage corresponding to a required screenupdate is applied by the pixel electrodes to the data lines, and adifferential voltage is applied to the pixel electrodes via theirrespective switching elements, causing pigment particles suspended inthe dielectric fluid of respective display systems to migrate in thedirection of the applied field. To fix a position of the particles, auniform voltage is then applied to respective pixel electrodes via theirswitching elements, and the switching elements are then turned off.

It is to be noted that in the present invention, voltages are applied asrequired, via switching elements, to respective pixel electrodes,thereby creating a matrix in the electrophoretic display. In the methodfor driving the electrophoretic display of the present invention, eachof the pixel electrodes is first subject to a preset uniform voltageapplied by the common electrode. Scanning lines are then selectedsequentially. Next, a voltage differential corresponding to a desireddisplay update is applied via the switching elements to their respectivepixel electrodes, whereby designated pigment particles are caused tomigrate. To maintain a desired display state, a uniform voltage isapplied to each of the pixel electrodes via respective switchingelements, and, further, a break voltage is applied to counter inertialmovement of the suspended pigment particles in each of the particledispersion systems, and finally the switching elements are turned off.

According to the present invention, an active matrix electrophoreticdisplay can be realized by applying differential voltages via aplurality of switching elements to a plurality of corresponding pixelelectrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is an exploded perspective view showing a mechanicalconfiguration of an electrophoretic display panel based on the firstembodiment of the present invention;

FIG. 2 is a partial sectional view of the panel;

FIG. 3 shows a block diagram of an electrical configuration of anelectrophoretic display having the panel;

FIG. 4 is a simplified partial sectional view of the divided cell of thepanel;

FIG. 5 exemplifies the relation of the voltage between the twoelectrodes and the divided cell;

FIG. 6 is block diagram of the data line drive circuit 140A of theelectrophoretic display;

FIG. 7 is a timing chart of the scanning drive circuit 130A and the dataline drive circuit 140A;

FIG. 8 is a timing chart showing the outputted data from the imageprocessing circuit 300A;

FIG. 9 is a timing chart of the electrophoretic display in the resettingoperation;

FIG. 10 is a timing chart of the electrophoretic display in the writingoperation;

FIG. 11 is a timing chart of the resetting operation in the secondmanner;

FIG. 12 is a timing chart of the resetting operation which resetshorizontal lines simultaneously;

FIG. 13 illustrates the horizontal lines to be rewritten;

FIG. 14 illustrates the reset operation by the region;

FIG. 15 is a block diagram of the electrical configuration of theelectrophoretic display panel in the fifth manner;

FIG. 16 is a simplified partial sectional view of the divided cell ofthe electrophoretic display;

FIG. 17 is a block diagram showing the configuration of the image signalprocessing circuit 300A′ based on the second embodiment.

FIG. 18 is a timing chart of the outputted data from the image signalprocessing circuit 300A′;

FIG. 19 exemplify the relation of the gradation voltage and thedifferential gradation voltage.

FIG. 20 is a timing chart of the electrophoretic display in the writingoperation;

FIG. 21 is a block diagram of the image signal processing circuit 300Bof the electrophoretic display based on the second embodiment;

FIG. 22 is a timing chart of the outputted data from the image signalprocessing circuit 300B;

FIG. 23 is a block diagram of the data line drive circuit 140B thereof;

FIG. 24 is a bloc diagram of the detailed configuration of the selectioncircuit 144B in the data line drive circuit 140B;

FIG. 25 is a timing chart showing the operation of the selection circuit144B;

FIG. 26 is a timing chart of the electrophoretic display in the writingoperation;

FIG. 27 is a block diagram of the image signal processing circuit 300B′based on the forth embodiment;

FIG. 28 is a timing chart of the electrophoretic display in the writingoperation in the second embodiment;

FIG. 29 is a timing chart of the electrophoretic display based on thefifth embodiment;

FIG. 30 is a timing chart of the electrophoretic display in the writingoperation;

FIG. 31 is a timing chart showing a whole operation of theelectrophoretic display based on the sixth embodiment;

FIG. 32 is a timing chart of the electrophoretic display in the writingoperation based on the sixth embodiment;

FIG. 33 is a timing chart of the whole operation pf the electrophoreticdisplay based on the seventh embodiment;

FIG. 34 is a timing chart of the electrophoretic display in the writingoperation;

FIG. 35 is a timing chart showing whole operation of the electrophoreticdisplay based on the eighth embodiment;

FIG. 36 is a timing chart of the electrophoretic display in the writingoperation based on the eighth embodiment;

FIG. 37 is a block diagram of a timer apparatus;

FIG. 38 is a block diagram of the timer apparatus in the writingoperation;

FIG. 39 is an external perspective view of an electronic book as oneexample of electronic devices;

FIG. 40 is an external perspective view of a personal computer asanother example of electronic devices;

FIG. 41 is an external perspective of a mobile phone as another exampleof electronic devices;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the accompanying drawings, preferred embodiments of thepresent invention will now be described.

(A) First Embodiment

An electrophoretic display of the present embodiment displays an imageaccording to an input image signal (VID). It is able to display bothstatic and animated images, but is particularly suited to displayingstatic images.

(A-1) Outline of an Electrophoretic Display

FIG. 1 is an exploded perspective view showing the mechanicalconfiguration of an electrophoretic display panel A, according to thefirst embodiment of the present invention.

FIG. 2 is a partial sectional view of the panel.

As shown in FIGS. 1 and 2, an electrophoretic display panel A has anelement substrate 100 and an opposing substrate 200. Element substrate100 is made of glass, a semiconductor or some other suitable material.Opposing substrate 200 is made of glass or some other suitabletransparent material. A common electrode 201 is formed on opposingsubstrate 200. A plurality of pixel electrodes 104 are formed on elementsubstrate 100 to constitute a plurality of pixels, each of whichcorresponds to one unit of an image. Substrates 100 and 200 are providedin opposing relation to each other such that electrodes formed on thesurfaces of the substrates face each other at regular intervals. Betweenthese electrode surfaces, bulkheads 110 are provided which divide theelectrode surfaces into a plurality of spaces, with each spaces facing,respectively, pixel electrodes 104. These spaces are referred tohereinafter as divided cells 11C. Each divided cell 11C is provided witha dispersal system 1 comprising a dielectric fluid 2 in which pigmentparticles are suspended. If required, the dielectric fluid 2 can beprovided with an additive such as a surface-active agent. In dispersalsystem 1, to avoid sedimentation of pigment particles 3 under gravity,both the dielectric fluid 2 and pigment particles 3 are selected to beapproximately equal in specific gravity to each other.

In this embodiment, an electrostatic field is applied to dispersalsystem 1 in each divided cell 11 to move the pigment particles in thesystem to a desired position which corresponds to a desired colorgradation of the pixel. It is possible to provide a large number ofdivided cells 11C in the bulkhead 110, and the range in which pigmentparticles 3 are able to migrate is thereby limited to the inner space ofeach divided cell 11C. In the dispersal system 1, migration of particlesmay be uneven or the particles may condense to form a lump. However,using a plurality of divided cells 11C in the bulkhead 110 prevents sucha phenomenon from occurring, and as a result the quality of imagesdisplayed is improved. In electrophoretic display panel A, each pixel iscapable of displaying one of the three primary colors (RGB). This isachieved by effecting three different types of dispersion in thedispersal system corresponding to R, G and B colors, respectively. Thus,when it is required to express dispersal system 1, dielectric fluid 2,and pigment particles 3 as a separate primary color each, subscripts“r,” “g,” and “b” are appended respectively to each element.

Thus, in this embodiment, dispersal system 1 r corresponding to R colorhas red particles as the pigment particles 3 r and the dielectric fluid2 r is a cyanogen color medium. The pigment particles 3 r are made ofiron oxide, for example. The dispersal system 1 g corresponding to Gcolor uses green particles as the pigment particles 3 g and thedielectric fluid 2 g is a magenta-color medium. The pigment particles 3g are made of cobalt-green pigment particles, for example. The dispersalsystem 1 b corresponding to B color uses blue particles as the pigmentparticles 3 b and the dielectric fluid 2 b is a yellow medium. Thepigment particles 3 b are made of cobalt-blue pigment particles, forexample.

That is, the pigment particles 3 that correspond to each color to bedisplayed are used, while the dielectric fluid 2 of a certain color (thecomplementary color, in this embodiment) that absorbs the color to bedisplayed is used.

The opposing substrate 200, the common electrode 201, and the sealer 202are transparent, enabling a user to see images displayed the opposingsubstrate 200. Thus, if pigment particles 3 migrate towards to thedisplay-surface-side electrode, they will reflect light of a wavelengthcorresponding to the color to be displayed. On the other hand, when thepigment particles 3 migrate to the opposite-side electrode to thedisplay surface, light of a wavelength corresponding to the color to bedisplayed is absorbed by the dielectric fluid 2. In this case, suchlight will not be visible to a user, and therefore no color will bevisible. In the present invention, a strength of an electrostatic fieldapplied to the dispersal system 1 determines how the pigment particles 3are distributed in the direction of thickness of the dispersal system 3.The combined use of the pigment particles 3, the dielectric fluid 2which absorbs light reflected by pigment particles 3, and controllingthe dielectric field strength enables adjustment of light reflectance ofa color. As a result, a strength of light reaching an observer can becontrolled.

A display area A1 and a peripheral area A2 partitioned by bulkheads 110are provided on the surfaces of the element substrate 100 which facesthe opposing substrate 200. In the display area, in addition to thepixel electrodes 104, thin film transistors (hereinafter, referred to asTFTs) are employed as scanning and data lines, and switching elementsare also employed and will be described later. In the peripheral area A2of the surface of the element substrate 100, a scanning line drivecircuit, a data line drive circuit, and externally connected electrodeswhich will be described later are formed.

FIG. 3 is a block diagram showing the electrical configuration of theelectrophoretic display. As shown, the electrophoretic display isprovided with the electrophoretic display panel A; a peripheral circuitincluding an image processing circuit 300A; and a timing generator 400.The image processing circuit 300A generates image data D by compensatinginput image signal VID based on the electrical characteristics of theelectrophoretic display panel A and outputs reset data Drest for apredetermined period before it outputs the image data D.

The reset data Drest is used for attracting pigment particles 3 to thepixel electrodes 104 so that their positions are initialized. In thisembodiment, dielectric fluid 2 is dyed black and pigment particles 3consist of titanium oxide, which has a whitish color, and for in thisexplanation will be described as having a positive charge. Timinggenerator 400 generates several timing signals synchronously with imageD, described later for a scanning drive circuit 130 and data line drivecircuit 140A.

In display area A1 of electrophoretic display panel A, a plurality ofscanning lines 101 are formed in parallel to an X-direction, while aplurality of data lines 102 are formed in parallel to a Y-directionwhich is orthogonal to the X-direction. A TFT 103 and a pixel electrode104 are positioned to provide a pixel in the vicinity of each of theintersections made by these scanning lines 101 and data lines 102. Hencethe pixels are mapped in a matrix by the intersections made betweenscanning lines 101 and data lines 102. The gate electrode of TFT 103 ofeach pixel is connected to a particular scanning line 101 for the pixeland a source electrode thereof is connected to a particular data line102 for the pixel. Moreover, a drain electrode of the TFT is connectedto pixel electrode 104 of the pixel. Each pixel is composed of a pixelelectrode 104, a common electrode 201 formed on opposing substrate 102,and dispersal system 1 provided between the substrates on which thecommon and pixel electrodes are provided, respectively.

Scanning line drive circuit 130 and data line drive circuit 140,consisting of TFTs, are made using the same production process as pixelTFTs 103. This is advantageous in terms of integration of elements andproduction costs.

When a scanning signal Yj is brought to its active state, TFTs 103 onthe jth scanning line 101, to which signal Yj is supplied, data linesignals X1, X2, . . . , Xn are provided sequentially to pixel electrodes104. On the other hand, the common voltage Vcom is applied from a powersupply, not shown, to the common electrode on opposing substrate 200.This generates a dielectric field between each pixel electrode 104 andcommon electrode 201 on opposing substrate 200. As a result, the pigmentparticles 3 within dispersal system 1 migrate to and an image isdisplayed using gradations based on image data D on a pixel-by-pixelbasis.

(A-2) Principle of Displaying

FIG. 4 is a cross-sectional view of a simplified structure of dividedcell 11C. In this embodiment, firstly the reset operation is carriedout.

Supposing that pigment particles 3 are positively charged, an operationis conducted to apply a voltage to pixel electrode 104, which hasnegative polarity relative to that of common electrode 201, and pigmentparticles 3 are attracted to pixel electrode 104 as shown in FIG. 4A.Next, a positive-polarity voltage is applied to pixel electrode 104, thevoltage corresponding to a gradation to be displayed as shown in FIG.4B. And the pigment particles migrate towards common electrode 201following the dielectric field. When the potential difference is madezero, no dielectric field is applied to the particles, and they stopmoving as a result of fluid resistance. In this case, since the velocityof the particle is determined by a strength of an applied dielectricfield, that is, the migration time of a particle is determined by anapplied voltage, if the duration is constant, changing the appliedvoltage will lead to a change in average position of pigment particles 3in the direction of thickness.

Incident light from common electrode 201 is reflected by pigmentparticles 3 and this reflected light reaches observer's eye throughcommon electrode 201. Incident and reflected light are absorbed indielectric fluid 2 and the absorption rate is proportional to theoptical path length. Hence a gradation recognized by an observer isdetermined by the positions of pigment particles 3. As mentioned above,since the positions of pigment particles 3 are determined by an appliedvoltage over a constant period, a desired gradation will be displayed.

Dispersal system 1 comprises a large number of pigment particles. Ifthey all have the same properties, such as electrical property (forinstance, charge), mechanical properties (for instance size, mass,) andother properties, they will behave in the same manner.

However the thickness of a divided cell 11C is made to be from a few upto a maximum of 10 micrometers, and thus a maximum migration length ofpigment particle 3 is very short. Consequently, to improve image displaycharacteristics, an infinitesimal migration length must be controlled.To achieve this, low voltages to effect a gradation must be used, whichmakes gradation control difficult.

To assist in control, pigment particles are provided with differingproperties. These differences enable a statistical distribution to beachieved of positions of pigment particles. FIG. 5 shows an example of arelation between a voltage applied between a common and pixel electrodesand the gradation displayed. The time fame for voltage application is 50milliseconds and the average voltage applied to migrate pigmentparticles 3 to common electrode 201 is 5 volts; and the standarddeviation of the distribution is 0.2 volts normalized with 5 volts.

In this figure, a solid line shows the characteristics of gradationaccording to the applied voltage and dotted line shows the probabilitydensity function. Probability density is the number of particles thathave reached the common electrode 201 which is normalized with 5 volts.

As shown therein, when the applied voltage is lower than 4.5 voltspigment particles merely reach the common electrode 201, but when theapplied voltage is 5 volts, half the particles 3 reaches to it, and thevoltage is higher than 5.5 volts almost all of them reaches. Thereforean applied voltage should be controlled in the range from 4.5 to 5.5volts to obtain the desired color gradation image.

(A-3) Drive Circuit

As shown in FIG. 3, the scanning drive circuit 130 has a shift resisterand sequentially shifts a Y-transfer start pulse DY which becomes becomeactive at the beginning of vertical scanning lines based upon a Y-clocksignal YCK and its inverted Y-clock YCKB and generates scanning linesignals Y1, Y2, . . . , Ym. As shown in FIG. 7, scanning signals whichsequentially shift their activating period (the the H-level period) aregenerated and outputted to each scanning line 101.

FIG. 6 shows a block diagram of the scanning line drive circuit 140A.Data line driving circuit 140A has an X-shift resister 141, a bus BUSwhich is supplied image data composed of 6 bits, switches SW1, . . . ,SWn, a first latch 142, a second latch 143, a selection circuit 144 anda D/A converter 145.

Firstly, the X-shift resister 141 sequentially shifts a X-transfer startpulse DX to generate sampling pulse SR1, SR2, . . . , SRn sequentiallyaccording to the X-clock XCK and its inverted X-clock XCKB.

Secondly, the bus BUS is connected to the first latch 142 through theswitch SW1, . . . , SWn and sampling pulses SR1, SR2, . . . , SRn aresupplied to each input terminal with the corresponding switch. A switchSWj is a set of 6 switches according to the 6 bits image data. Hence theimage data D is, at a time, imported to the first latch 142synchronously with with each sampling pulse SR1, SR2, . . . , SRn.

The first latch 142 latches image data D supplied from switch SW1, . . ., SWn and outputs it as dot-sequential data Da1, . . . , Dan. The secondlatch 143 latches each dot-sequential data Da1, . . . , Dan with a latchpulse LAT, which becomes active in every horizontal scanning time. Thesecond latch 143 generates line-sequential data Db1, . . . , Dbn fromdot-sequential data Da1, . . . , Dan.

The common voltage data Dcom generated in the image processing circuit300A and a no-bias timing signal Cb generated in the timing generator400 is supplied to the selection circuit 144.

The data Dcom is data which sets the voltage which is supplied to thecommon electrode 201 (ground level, for instance). The no-bias timingsignal Cb becomes active (the H-level) from a certain point to the endin a horizontal scanning time.

The selection circuit 144, when non-bias timing signal is active,selects the common voltage data Dcom, while when it is inactive, selectsline-sequential data Db1, . . . , Dbn to output data Dc1, . . . , Dcn asshown in FIG. 7. The D/A converter 145 converts data Dc1, . . . , Dcn, 6bits digital data into analog signal and generates this as each dataline signal X1, . . . , Xn and supplies it to each data line 102.

(A-4) Operation in an Electrophoretic Display

FIG. 8 shows a timing chart of an output data from the image signalprocessing circuit 300A. Outline of the operation will be describedreferring to FIG. 8.

Firstly, at time t0, the image signal processing circuit 300A, timinggenerator 400 and electrophoretic display panel A is turned the power onwhen the power supply of the electrophoretic device is switched on.

After the circuit is stabilized, the image signal processing circuit300A outputs the reset data Drest over a period of one scanning field.In the example shown in FIG. 8, the scanning field starts at time t1. Atreset time Tr, pigment praticles 3 are attracted to the pixel electrodes104 and their positions are initialized as described above.

While a data line drive circuit 104A outputs the reset voltages Vrest toeach data line 102 according to data values of Drest, the scanning linedrive circuit 130 sequentially selects each the line 101, with theresult that the reset voltage Vrest is applied to all the pixelelectrodes 104.

Next, a writing period Tw begins at a time t2. In this writing periodTw, the image signal processing circuit 300A outputs image data D overone scanning field.

The gradation voltages V are applied to each pixel electrode 104corresponding to the gradation to be displayed so that a section ofdisplay image is completed.

After next, in a holding period Th which starts with time t3 and endswith time t4, the image is held which is written in the immediatelypreceding writing period Tw. Its length can be set freely. In thisperiod, the image signal processing circuit 300A halts and outputs nodata and no electrostatic field is generated between the pixelelectrodes 104 and the common electrode 201. The pigment particles 3 donot change position unless they are subject to an electrostatic field,and consequently, a static image is displayed over the period.

Next, in the period which begins with time t4 and ends with t6, theimage is rewritten. In a similar way in the period that is from time t1to time t3, the writing operation subsequent to the reset operation iscarried out so that the displayed image is renewed.

(1) Resetting Operation

FIG. 9 is a timing chart of an electrophoretic display in a resettingoperation. As mentioned above, in the reset period Tr, the reset dataDrest is supplied to the data line drive circuit 140A. In this period,no-bias signal is inactive (the L-level) as shown in FIG. 9, as aresult, the voltages of data lines signals X1, . . . , Xn are all equalto the reset voltage Vrest.

In this embodiment, the reset voltage Vrest is negative compared to thecommon voltage Vcom of the common electrode, because the pigmentparticles are positively charged.

At this time, when the scanning signal Y1 becomes active (the H-level),TFTs 103 in the first line are switched on and the reset voltage Vrestis applied to each pixel electrode 104. After that, reset voltage Vrestis applied to each pixel electrode 104 of the second, third, . . . , mthlines. For exemple, at time tx, when the scanning line signal Y1 is madeinactive, each TFT 103 in the first line is switched off so that thepixel electrodes 104 and data lines 102 are cut off. However capacityhas been created in the system comprised of the pixel electrode 104,dispersal system 1 and the common electrode 201. Hence if each TFT 103is switched off, the reset voltage Vrest is maintained between the pixelelectrode 104 in the first horizontal line and the common electrode 201.

In that way reset voltage Vrest is applied between the two electrodes,pigment particles 3 in the dispersal system 1 are attracted and theirpositions are initialized.

(2) Writing Operation

FIG. 10 shows a timing chart of the electrophoretic display in anoperation of writing. Here is depicted about ith line (ith scanningline) and jth column (jth data line) but it is obvious that other pixelscan betreated likewise. In the following, the pixel of ith line and jthcolumn is represented by Pij, the gradation voltage to be displayed inthe pixel Pij is represented by Vij and the brightness if Pij isrepresented by Iij.

Since each data line X1, . . . , Xn is generated through the D/Aconversion of data Dc1, . . . , Dcn as shown in FIG. 7, the voltage ofthe data line signal Xj is, as shown in FIG. 10, equals to the gradationvoltage Vij in the voltage applied period Tv from time T1 to time T2,while to the common voltage Vcom in the no-bias period Th from time t2to time t3.

The scanning line signal Y1 supplied to the ith scanning line 101 isactive during the period of the ith the horizontal scanning. Therefore,the TFT 103 which comprises the pixel Pij is switched on over thatperiod and the data line signal Xj from time T1 to time tme T3 isapplied to the pixel electrode 104. That is, in this embodiment, anoperation that begins with applying the gradation voltage Vij to thepixel electrodes 104 and ends with applying the common voltage Vcomthereto is completed within a period of one horizontal line scanning.

In the following, the pigment particles' motion will be described in thepixel Pij. Being done the reset operation before the writing operationbegins, at time T1, all pigment particles of the pixel Pij arepositioned on the side of the pixel electrode 104. At this time when thevoltage 104 Vij is applied to the pixel electrode 104, an electrostaticfield is generated in the direction of from the pixel electrode 104 tothe common electrode 201. Thus the particles 3 start to move at time T1.

In this embodiment, since the particles 3 are white and dielectric fluid2 is black, the more pigment particle 3 is nearing to the commonelectrode 201, the higher the brightness Iij of the pixel Pij is. As aresult, Iij is becomes higher gradually from time T1 as shown therein.

Since the pixel Pij is composed of a dispersal system 1 sandwiched by apixel electrode 104 and the common electrode 201, it has the capacitancedepending upon the area of the electrodes, the distance between the twoelectrodes, and dielectric constant of the dispersal system 1.

Accordingly, even if TFT 103 is turned OFF to brake supplying charges tothe pixel electrode 104, since the capacitor accumulates some charge,electrostatic field with a constant strength being generated between thetwo electrodes. Thus, since pigment particles 3 continue to migrate tocommon electrode 201 for as long as an electrostatic field is applied, aperiod in which generation of the electrostatic field is stopped, inother words, a process to remove extra charges accumulated in thecapacitance is required. Consequently, the no-bias period Tb is set.

In the no-bias period Tb, since the common voltage Vcom is applied tothe pixel electrode 104, the pixel electrode 104 and the commonelectrode 201 becomes equipotential at time T2. This means noelectrostatic field is applied to pigment particles 3 from that time. Ifthe fluid resistance of the dielectric fluidis, to some extent, large,the particles 3 stop moving at time T2 when no electrostatic fieldexists. This results in a constant value of brightness Iij from time T2as shown therein.

If the value of the fluid resistance of the dielectric fluid 2 is small,the pigment particles 3 keep moving for a period due to their inertia.In this case, the image D which is compensated beforehand by taking theabove effect into account is generated in the image signal processingcircuit 300A.

In this operation of writing, brightness Iij of the pixel Pij can becontrolled based on the gradation to be expected such that after thevoltage Vij is applied to the pixel electrode 104 to move the pigmentparticles 3 by the distance according to the gradation to be displayed,then the common voltage Vcom is applied thereto to brake the movingpigment particles.

In this embodiment the common voltage Vcom is applied to brake pigmentparticles 3, but it is not necessary to apply the same voltage, whichcompletely equals to the common voltage Vcom, instead any voltage, whichis able to brake moving pigment particles 3 is possible.

Since the particles 3 are not able to migrate simply by overcoming fluidresistance, if the value of the fluid resistance of the dielectric fluidis large it may be necessary to apply a voltage which is somewhatdifferent from the common voltage Vcom.

(3) Holding Operation

In FIG. 7, at time T3, since the scanning line signal Y1 shifts fromactive to inactive, the TFT 103 of the pixel Pij is turned off. Asmentioned above, in the no-bias period Tb, since the common voltage Vcomis applied to the pixel electrode 104, no electrostatic field isgenerated between the two electrodes. Therefore no electrostatic fieldis applied to the dispersal system 1 unless a new voltage is applied.This enables the position pigment particles 3 to be held, and thus adisplayed image to be held.

In such a holding period Th, since there is no need to apply a voltageto pixel electrodes 104, and consequently neither the scanning linesignal Y1, . . . , Ym nor the data line signal X1, . . . , Xn need begenerated, thereby enabling a reduction in power consumption in thisperiod as follows:

First the main power supply of the electrophoretic display is turnedoff. This means that the electrophoretic display panel and peripheraldevices such as the image signal processing circuit 300A and the timinggenerator 400 halt and no power is consumed.

The second is to brake supplying power to the electrophoretic displaypanel A. This reduces power consumption.

The third is to stop supplying the Y-clock YCK, the inverted Y-clockYCKB, the X-clock XCK, the inverted X-clock XCKB to the scanning linedrive circuit 130, and the data lines driving circuit 140A. Since thescanning line drive circuit 130 and the data line drive circuit 140A ismade of complementary TFTs as described above, power is consumed onlywhen the current is fed therethrough, in other words, inversion of alogic level occurs. Consequently, stopping the supply to the clocksenables a reduction in power consumption.

(4) Rewriting

Rewriting is carried out as follows:

The first method is as follows. After a reset operation is carried out,as described above, sequentially on a line-by-line basis, the writingoperation is also carried out sequentially on a line-by-line basis, anda common voltage followed by a gradation voltage is applied to the pixelelectrodes 104. This enables frame rewrite of an image.

The second method consists of a resetting and rewriting operationcarried out only in the lines where rewriting is required. Suppose thejth and the j+1th lines are to be rewritten by way of example. FIG. 11shows a timing chart describing an operation of resetting in thismethod.

The second method is that, in the resetting period Tr, the image signalprocessing circuit 300A outputs the reset data Drest. And at this time,the scanning line driving circuit 130 sequentially outputs the scanningsignal Y1, . . . , Yj, Yj+1, . . . , Ym as shown therein. While theno-bias timing signal Cb is in the L-level during the scanning line 101necessary to be rewritten is selected. Since jth and j+1th lines arerewritten, the no-bias timing signal Cb is in the L-level (inactive)when the scanning line signal Yj and Yj+1 are active.

As described above, while the selection circuit 144 (cf. FIG. 6) outputsthe common voltage data Dcom during the no-bias timing signal Cb is inthe H-level (active) and outputs the outputted data Db1, . . . , Dbn ofthe latch 143 during the no-bias timing signal Cb is in the low level.In other words, in the period which jth and j+1th scanning line 101 areselected, the reset voltage Vrest is supplied to all data lines 102,while in the other selected time of the scanning line 101, the commonvoltage Vcom is applied to all data lines 102.

Therefore while the common voltage Vcom is applied to the pixelelectrodes 104 on from the first to the j−1th line and from the j+2th tothe mth line, the reset voltage Vrest is applied to the pixel electrodes104 of the jth and j+1th line, so that the pixels of the j th and j+1thlines are initialized. Since applying the common voltage Vcom to thepixel electrodes 104 generates no electrostatic field, the positions ofpigment particles 3 in the pixels on from the first to the j−1th lineand from the j+2 to the mth line don't change.

In the writing operation, writing is carried out in the manner as shownin FIG. 7, so that the image signal processing circuit 300A outputs theimage data D to the line to be rewritten, while the common voltage dataDcom to the other lines. This enables rewriting only in the jth andj+1th lines.

The third method is that after a plurality of electrodes is reset, theyare rewritten in the usual way. In the above second method, a resetoperation is carried out line by line in such a way that first the jthline is reset then the j+1th line is reset and so on.

However, it is possible to reset simultaneously if a scanning line drivecircuit which simultaneously select a plurality of scanning lines 101 tobe rewritten. For example, as shown in FIG. 12, it is obvious that it ispossible to reset simultaneously jth and j+1th line to be rewritten ifthe reset voltage Vrest is applied to the data lines 102 activating onlythe scanning line signal Yj and Yj+1. Writing is carried out in theusual way, as shown in FIG. 7 that the image signal processing circuit300A outputs the image data D only in the line to be rewritten, then thecommon voltage data Dcom is outputted to the other lines. This methodenables rewriting only in the jth and j+1 line.

The fourth method is that after a region to be rewritten issimultaneously reset, a new voltage is applied to the pixels whichbelong to the region.

Suppose that the region R to be rewritten is from ath to bth line andfrom cth to dth column as shown FIG. 14.

First, the scanning line drive circuit is used which can rewritesimultaneously a plurality of the scanning lines 101 to be rewritten.The image signal processing circuit 300A outputs the data as the data ofone line, which is the common voltage data Dcom for from the first tothe c−1 th line and while is the reset data for from the cth to the Dthline and the common voltage data Dcom for from d+1th to the nth line.The no-bias timing signal remains to be inactive. This enables that thedata lines signal from X1 to Xc−1 and from Xd+1 to Xn is set to thecommon voltage Vcom during the horizontal scanning, while the data linessignal from Xc to Xd is set to be the reset voltage Vrest. In thehorizontal scanning period, the scanning line signal only from Ya to Ybcan be set to active so as to reset the region R. In writing, the imagesignal processing circuit 300A outputs the image data D to the pixelscorresponding to the region R, while the common voltage data Vcom to theothers. Rewriting only of the region R is carried out in this way.

The fifth method is carried out such that after all the pixels are resetsimultaneously, rewriting is carried out in the ordinary manner ofwriting. FIG. 15 shows a block diagram of the electrophoretic displaypanel B in this manner. The electrophoretic display panel B has the sameconfiguration as the electrophoretic display panel A shown in FIG. 3except that TFTs 105 are set in each line and that the image scanningdriving circuit 130B is able to simultaneously become active thescanning line signals from Y1 to Ym.

In FIG. 5 the reset voltage Vrest is applied to source electrodes oneach TFT 105 and reset timing signal Cr is applied to gate electrodesthereon and those drain electrodes is connected with each data lines102. The reset timing signal Cr generated in the timing generator 400becomes active during the reset period Tr. When the reset timing signalCr is active, all TFTs is turned on simultaneously so that the resetvoltage Vrest is applied to each data line 102. On the other hand, thescanning driving circuit 130B makes all scanning line signals activewhen the reset timing signal Cr is turned to active.

Hence the reset voltage Vrest is applied to all the pixels 104 duringthe reset timing signal Cr is active. This leads to the simultaneousresetting of all the pixels.

In this case, it may be possible that source electrodes on each TFT tobe set at ground level, and the voltage, instead of the common voltageVcom, is used to apply a positive voltage with reference to the groundpotential which is sufficient to initialize. That is, with reference toeither a pixel electrode 104 or the common electrode 201, sufficientvoltage to initialize another electrode is applied.

It is also possible for the voltage for initializing to be applied tothe pixel to which the region of the image to be rewritten belongs.

(B) Second Embodiment

In the above embodiment, rewriting is carried out in a way that after areset operation as shown in FIG. 16A is carried out, then a writingoperation is carried out shown in FIG. 16B to renew a displayed image.In this case, the positions of the pigment particles 3 are initializedin displaying a subsequent image. In the case that dielectric fluid 2 iscolored black and the pigment particles 3 are colored white, a black outoccurs across the entire image. However, if a change in image iseffected sufficiently rapidly, it will not be visible to the naked eye.Nevertheless there is a case that the resetting operation needs a longtime according to physical property of the dispersal system 1, whichresults in the fact that change of the brightness in initializing thepigment particles 3 can be detected.

In order to deal with the above situation, it is possible that thevoltage which corresponds to the difference between the average positionto be displayed next and that corresponding to the presently displayedimage is applied between the two electrodes for a constant time. Supposethe present gradation is 50% and the gradation to be displayed next is75%, for example. If the average position of the pigment particles 3 is50% the thickness direction of the dispersal system 1, the gradationdisplayed is 50%, as shown in FIG. 16B. In order to change thisgradation to that of 75%, it is necessary to move the particles 3 to aposition of ¾ in the thickness direction. Consequently the voltage,which corresponds to the difference between the gradation to be nextdisplayed and that of now displayed, is applied to the pixel electrodes104 to move the pigment particles 3 to the appropriate position. Thisrealizes a renewing of a displayed image without a resetting operation,which will lead to smooth displaying of an animation. In the following,only a difference compared to the first embodiment will be described.

(B-1) Image Signal Processing Circuit 301A

FIG. 17 is a block diagram showing a configuration of a image signalprocessing circuit 301A. The image signal processing circuit 301A iscomprised of an A/D converter 310, a compensation part 320, acalculation part 340. An externally supplied signal VID is supplied tothe compensation part 320 through the A/D converter 310 as an inputimage data Din. The compensation part has a ROM and others and generatesan image data Dv undergoing compensation processing such as gammacorrection, and output it to a calculation part 330.

The calculation part 330 has a memory 331 and a subtracter 332. Thememory 331 has the first field memory 331A in which writing is executedin odd fields, while reading is executed in even field and has thesecond field memory 331B in which writing is executed in an even field.The memory 331 delays the image data Dv by one field which is suppliedto the other input terminal of the subtracter 332 as the delayed imagedata Dv′.

Then the subtracter 332 generates the differential image data Dd bysubtracting the delayed image data Dv′ from the image data Dv and outputit. The selection part 340 selects the reset data Drest in the resetperiod Tr, while outputs the differential image data Dd in the wirtingperiod Tw. It should be noted that, in the first field, since there isno delayed image data Dd, a dummy data whose value is ‘0’ is supplied tothe other input terminal of the subtracter 332. Hence the image data Dvis outputted as the differential image data Dd in the first field. Ifthe delayed image data Dv′ is the present gradation displayed, the imagedata Dv is equivalent to the gradation to be displayed next. Thereforethe differential image data Dd is equivalent to the data whichcorresponds to the difference between the gradation to be next displayedand that of now displayed.

Since configurations of drive circuit and data line circuit in thisembodiment is similar to that of the first embodiment, explanation isomitted.

(B-2) Operation in the Second Embodiment

FIG. 18 is a timing chart showing the output data from the image signalprocessing circuit 301A.

First, at time t2, the writing period Tw begins. In this period, theimage signal processing circuit 301A output the differential image dataDd. Hence the differential voltage Vd, which corresponds to thedifference between the gradation to be next displayed and the presentgradation, is applied to each pixel electrode 104 except that in thefirst field (from time t2 to t3), the image data Dv is supplied as thedifferential image data Dd to the data lines drive circuit 130, whichmeans that the voltage to be displayed is applied to each electrode 104.However, since, at time t2, the gradation displayed is set to 0% (or100%) having done the resetting, the operation in the first period isessentially equivalent, in the viewpoint of it's basic function, to thatthe differential voltage Vd which corresponds to the difference betweenthe gradation to be next displayed and the present gradation is appliedeven in the first field.

Similarly, after the image is displayed in the first field, the voltagewhich corresponds to the gradation difference is applied in the nextfield and so in the following field.

For instance, if the gradation voltage at a pixel changes such as v1,v2, . . . , v7 accordingly from the first field F1 to the seventh fieldF7 as shown in FIG. 19A, the differential voltage Vd are Vd1, Vd2, . . ., Vd7 accordingly as shown in FIG. 19B.

In the holding period Th (after time t5), a static image is displayedlikewise in the first embodiment.

(B-3) Writing Operation

FIG. 20 shows a timing chart of the electrophoretic display in thewriting operation. Here is depicted about ith line (ith scanning line)and jth column (jth data line) but it is obvious that other pixels canbe, of course, dealt likewise. In the following, the pixel of ith lineand jth column is represented by Pij, the differential voltage to bedisplayed in the pixel Pij is represented by Vdij and the brightness ofPij is represented by Iij. Suppose the pixel Pij displayed 10% in thenext previous field and also required voltage to change from thedisplayed gradation 0% (all pigment particles 3 are on the side of thepixel electrodes 104) to the displayed gradation 100% (all pigmentparticles are on the side of the common electrodes is represented by+V100 with respect to the common voltage Vcom. Similarly, requiredvoltage to change from 100% to 0% is represented by −V100.

Since each data line X1, . . . , Xn is generated through the D/Aconversion of data Dc1, . . . , Dcn as shown in FIG. 7, the voltage ofthe data line signal Xj is, as shown in FIG. 20, equals to thedifferential voltage Vdij in the differential voltage-applied period Tdvfrom time T1 to time T2, while to the common voltage Vcom in the no-biasperiod Tb from time t2 to time t3.

Provided that the gradation to be displayed in the present field 50%,the value of the differential voltage Vdij is −V50 indicated as thesolid line therein because the voltage decreases by 50% from the nextprevious one. By another way of example, if the gradation to bedisplayed in the present field is 0%, the value of the Vdij is −V100indicated as the dotted line therein.

(C) Third Embodiment

In the first embodiment, as described before, after the gradationvoltage is applied to the pixel electrodes 104 to move the pigmentparticles 3 by the distance correspondent to the gradation to bedisplayed, the common voltage Vcom is applied to the pixel electrodes104 not to apply any electrostatic field to the particles 3.Additionally, the image data D is compensated at the image signalprocessing circuit 300A before outputting taking the inertia intoconsideration, in case of small fluid resistance of the dielectricfluid, which means that the particles 3 continue to move under inertia.

However, it can take a considerable time for pigment particles 3 tobecome stationary depending on the level of fluid resistance encounteredin dielectric fluid 2. In the above example, since pigment particles 3migrate away from pixel electrodes 104 to the common electrode, if thereis little fluid resistance the image displayed will not reach optimumbrightness in a desired time. In the third embodiment, anelectrophoretic display designed to prevent fluctuations in brightnessis provided. It is configured in the same manner as that of the firstembodiment shown in FIG. 3, except that image signal processing circuit300B and data line drive circuit 140B is used instead of the imagesignal processing circuit 300A and the data line processing circuit140A.

(C-1) Image Signal Processing Circuit

FIG. 21 is a block diagram of image signal processing circuit 300B andFIG. 22 is a timing chart for output data.

As shown in FIG. 21, an image signal processing circuit 300B is providedwith an A/D converter 310, a compensation part 320, a brake voltagegeneration part 330 and a selection part 340. The image signal VIDsupplied externally through the A/D converter is supplied to thecompensation part 320 as input image data Din. The compensation part isprovided with a ROM or other suitable memory and generates an image dataDv undergoing compensation processing such as gamma correction.

The brake voltage generation part 330 is provided with a table in whichthe brake voltage data Ds and image data D having values correspondingto those of of Ds are memorized. In this way, the brake voltage data Dsis acquired by accessing the table and using image data D as an address.The table is provided with storage circuits such as RAM or ROM.

The brake voltage data Ds corresponds to the brake voltage Vs, whichwill be described later, and is used to brake pigment particles 3. Asmentioned above, pigment particles 3 subject to inertial movement can bebraked by utilizing a electrostatic field Coulomb force the direction ofwhich is opposite to that of pigment particles 3. Since pigmentparticles 3 move in response to a gradation voltage for display of animage, it is necessary to apply an electrostatic field to them which isacting in an opposite direction, and the value of which is dependent onthe kinetic energy of pigment particles 3, in other words, the gradationvoltage V. Therefore, in this embodiment, taking into account fluidresistance of dielectric fluid 2 among other factors, the brake voltagedata Ds corresponding to the values of the image data D is memorized inthe table beforehand for reading.

As shown in FIG. 22, a selection part 340 outputs reset data in resetperiod Tr, while in the writing period, it outputs multiplex data Dm inwhich image data D and brake voltage data Ds are combined. If image dataD consists of 6 bits and brake voltage data Ds is also 6 bits, themultiplex data Dm will be 12 bits, which means that 6 bits from the mostsignificant bit (MSB) is the image data D and 6 bits from the latestsignificant bit (LSB) is the brake voltage data Ds.

(C-2) Data Line Drive Circuit

FIG. 23 shows a block diagram of a data line drive circuit 140B. In thisembodiment, it is configured similarly to a data line drive circuit 140Ain the first embodiment except that a first latch 142B and a secondlatch 143B latch 12 bits data and that a selection circuit 144B is usedinstead of a selection circuit 140B.

The first latch 142B generates dot-sequential data from Da1 to Danlatching 12 bits multiplex data Dm and the second latch 143B transformsthe dot-sequential data from Da1 to Dan into line-sequential data fromDb1 to Dbn. It should be noted that the reset data Drest in theresetting period is transformed into remains 6 bits line-sequential dataremaining 6 bits.

FIG. 24 shows a block diagram showing a detailed configuration of theselection circuit 144B and FIG. 25 shows the timing chart thereof. Asshown in FIG. 24, the selection circuit 144B has n selection units fromU1 to Un, each of which selects appropriate data from the image data Dand the brake voltage data Ds, which is comprising the multiplex data Dmand the voltage data Ds, and outputs it, depending on the no-bias timingsignal Cb and the stop timing signal Cb. The no-bias timing signal Cbbecomes active (the H-level) only in the period in which the commonvoltage data Dcom is selected like in the fist embodiment describedabove, while the top timing signal Cs becomes active (in the H-level)only in the period in which the brake voltage data Ds is selected.

The selection circuit 144B selects and outputs the image data D when theboth Cs and Cb is inactive (the L-level). When the Cs is active, itselects and outputs the brake voltage data Ds. When both Cs and Cbbecome active, it selects and output the common voltage data Dcom.

Suppose the multiplex data Dmi is supplied as the ith line-sequentialdata Dbi to the ith selection unit Ui in a certain horizontal scanningperiod as shown in FIG. 25, for example. In this case, it is the imagedata Di which is comprised of upper bits of the multiplex data Dm andthe brake voltage data Dsi which is comprised of the lower bits of Dmthat is supplied to the selection circuit 144B. In the voltage appliedperiod Tv, both the stop timing signal Cs and the no-bias timing signalCb is inactive, which means that the image data Di is selected. In thebrake voltage applied period Ts, the stop timing signal is active, withthe result that the brake voltage data Dsi is selected. Besides, in theno-bias period, the no-bias timing signal Cb is active, with the resultthat the common voltage data Dcom.

The selected data in this way is supplied to the D/A converter 145 inFIG. 23 and outputted to each data line 101 as the data line signal fromX1 to Xn.

(C-3) Operation of Electrophoretic Device

The operation of an electrophoretic display in this embodiment issimilar to that of the first embodiment described referring to FIG. 8,in a point of its sequence that starts with resetting, followed bywriting, holding, and ends with rewriting. However, it differs in havingthe process in which the brake voltage is applied to the pixelelectrodes 104 in writing (contains rewriting). In the following, thedifference, that is, details of the writing operation will be described.

FIG. 26 shows a timing chart of the electrophoretic device in thewriting operation. Here is depicted about ith line and jth column but itis obvious that other pixels can be, of course, dealt likewise. In thenext previous field, the pixel Pij has displayed the gradation 100%. Thevoltage of the data line signal, which is supplied to the jth data line102, equals to the gradation voltage Vij during the gradation voltageapplied period Tv which starts with T1 and ends with T2 as shown in FIG.26. In the period of the brake voltage applied period Ts from T2 to T3,it equals to the brake voltage Vs, and in the no-bias period Tb from T3to T4 it equals to the common voltage Vcom.

The scanning line signal Yi which is supplied to the ith scanning line101 is active in the ith scanning line period. Hence the TFT 103 whichcomprises the pixel Pij is turned on in this period, so that the pixelelectrode 104 imports the data signal Xj of from T1 to T4. Namely, inthis example, the operation which starts with applying the gradationvoltage Vij and ends with applying voltage of the common voltage Vcombetween the two electrodes is completed.

In the following, the pigment praticles' motions will be described inthe pixel Pij. Having been done the reset operation before the writingoperation begins, at time T1, all pigment praticles of the pixel Pij arepositioned on the side of the pixel electrode 104. At this time when thevoltage 104 Vij is applied to the pixel electrode 104, an electric fieldis generated which is in the direction of from the common electrode 201from to the pixel electrode 104. Thus pigment praticles 3 start tomigrate at time T1 and the brightness Iij is being gradually high.

At time t2, the brake voltage Vs is applied to the pixel electrodes 104.The value of the brake voltage Vs is set based on the gradation voltageVij which has been applied in the immediately previous period and hasnegative-polarity with respect to the common voltage Vcom. That isbecause the electric field to counteract Coulomb force must be applied,which was applied to the pigment praticles 3 in the direction of fromthe pixel electrodes 104 to the common electrode.

This brake voltage Vs, as it were, acts as a brake upon the particles 3to give them Coulomb force whose direction is opposite with respect totheir motions. With this operation the particles 3 stop moving untiltime T3 which is the end of the voltage applied period Ts.

At time T3, the common voltage is applied to the pixel electrodes 104.The voltage of the pixel electrodes 104 coincides with that of thecommon electrode 201 to take away the charge accumulated in theelectrodes. By doing so, any electric field isn't generated any longerand thus the positions of the pigment praticles 3 can be held.

In the writing operation of this embodiment, firstly the pigmentpraticles 3 migrate by applying the gradation voltage Vij, then theparticles 3 brake to stop by applying the brake voltage Vs. Thereforeeven if the viscous drag of the dispersion medium 2 is small, a distancewhich the pigment praticles 3 migrate until the particles 3 stop due totheir inertia can be short. This enables to display stable images in ashort time without fluctuation of brightness.

(D) Fourth Embodiment

In the third embodiment, the gradation voltage is applied. It is alsopossible to apply the differential voltage.

FIG. 27 shows a block diagram of the image signal processing circuit301B.

A brake voltage generation part 350 has a table in which the brakevoltage data Ds′ and a differential image data Dd whose values arecorrespondent to those of Ds′ are memorized. This means that the brakevoltage data Dds is to be acquired by accessing the table and pointingto the differential image data Dd as the address. The table isconfigured with storage circuits such as RAMs and ROMs.

The brake voltage data Dds corresponds to the brake voltage Vds, whichwill be described later, and is used for braking the pigment particle 3.As mentioned above, particles 3 continue moving due to their inertiaeven if the electric field is not applied to dispersal system 1 anylonger. But force moving in the opposite direction enables braking andstopping particles 3. Since the pigment particles 3 are moving accordingto the gradation voltage when the image is going to displayed, it isnecessary to apply an electric field whose direction is opposite and,furthermore, whose intensity is dependent on the kinetic energy ofparticles 3, in other words, the differential voltage Vd. Therefore, inthis embodiment, taking the fluid resistance of the dispersion medium 2and some other effects into consideration, the brake voltage data Ddscorresponding to the values of the differential image data Dd ismemorized in the table beforehand and is to be read the table asrequired.

The data line drive circuit and the selection circuit are similar tothose of the second embodiment, therefore explanation is omitted here.

(D-1) Operation of the Electrophoretic Device

FIG. 28 shows a timing chart of the electrophoretic display in thewriting operation. An ith line (ith scanning line) and a jth column (jthdata line) are depicted but it is obvious that other pixels can bedealtwith similarly. In the following, the pixel of the ith line and the jthcolumn is represented by Pij, the differential voltage to be displayedin the pixel Pij is represented by Vdij and the brightness of Pij isrepresented by Iij. Suppose the gradation in Pij was 10% in the nextprevious period.

A voltage of the jth line signal Xj, which is supplied to the jth dataline 102, as shown in FIG. 28, is equal to the differential voltage Vdijin the differential voltage applied period Tdv from time T1 to time T2.Provided that the gradation to be displayed in the present field is 50%,the value of the differential voltage Vdij is −V50 indicated as thesolid line therein, because the voltage decreases by 50% from theprevious one. By another way of example, if the gradation to bedisplayed in the present field is 0%, the value of the Vdij is −V100indicated as the dotted line therein. In the brake voltage appliedperiod Ts from time T2 to time T3, the voltage of the data line signalXj is equals to the brake voltage Vdsij. The value of the brake voltageVdsij corresponds to that of Vdij. In the no-bias period from time T3 totime T4, the voltage of the data line signal is equal to the commonvoltage Vcom.

(E) Fifth Embodiment

(E-1) Display

In the electrophoretic device of the first embodiment, the gradationvoltage applied period Tv and no-bias period Tb are set in the period ofone horizontal scanning. Motions of the pigment particles finish withinthe period.

Instead, in the electrophoretic devices of the fifth embodiment, agradation voltage applied period and a no-bias period are set on afield-to field basis. A configuration of this electrophoretic device issimilar to that of the first embodiment as shown in FIG. 3, except forthe period in which the no-bias signal timing Cb is active.

(E-2) Whole Operation

FIG. 29 shows a timing chart of the whole operation in theelectrophoretic display. As shown therein, the image signal processingcircuit 300A outputs the reset data Drest in the reset period Tr. Inthis period, pigment particles 3 are attracted to pixel electrodes 104so that their positions are initialized.

Next, a writing period is composed, of the gradation voltage appliedperiod Tvf and the no-bias period Tbf on a field-to-field basis. In thegradation voltage applied period Tvf, the gradation voltage is appliedto pixel electrodes 104 based upon outputted image data D outputted fromimage signal processing circuit 300A. But the no-bias signal Cb remainsinactive in that period hence the common voltage Vcom is not applied topixel electrodes 104.

While in the no-bias period Tbf, the image signal processing circuit300A does not supply any data but the no-bias timing signal Cb becomesactive, so that the common voltage Vcom is applied to all data lines102.

Therefore, the common voltage Vcom is applied to each of pixelelectrodes 104. That is, in this embodiment, the gradation voltage D isapplied in a certain period of a certain scanning line, then gradationvoltage V is maintained until the scanning line is again selected, thenthe common voltage Vcom is applied to pixel electrodes 104 in the nextperiod in which the scanning line is selected.

In the holding period Th, there is no electric field between the pixelelectrodes 104 and the common electrode 201, thus enabling holding theimage displayed in the previous writing period.

In the rewriting period, as in the displaying of the first period, aseries of the processing which entails resetting, applying thegradations voltage, applying the common voltage (no-bias), and so on iscarried out.

(E-3) Writing Operation

FIG. 30 is a timing chart of the electrophoretic display in the writingoperation. Pij which is on ith line and jth column is depicted, but itis obvious that other pixels can be described similarly. The voltage ofthe data line signal Xj which is supplied to the jth data line 102varies by the scanning line period in the gradation voltage appliedperiod Tvf as shown in FIG. 30. In the period of the ith scanning line,the data line signal Xj is equal to the gradation voltage Vij. At thistime, since the scanning line signal Yi becomes active (the H-level),the gradation voltage Vij is applied to pixel electrode 104, thereby, attime T1, shifting the voltage of pixel electrode 104 from the resetvoltage Vrest to the gradation voltage Vij so that the electric fieldcorresponding to the gradation to be displayed is applied to thedispersal system 1.

At time T2, when the scanning line signal Yi becomes inactive (theL-level), the TFT 103 of the pixel Pij shifts to OFF. However since somecharge is accumulated in the capacitor, the voltage of the pixelelectrode 104 remains the gradation voltage Vij.

In the period of the ith horizontal scanning in the no-bias period Thf,when the scanning signal Yi becomes active, the common voltage Vcom isapplied to pixel electrode 104. Therefore the voltage of pixel electrode104 coincides with the common voltage Vcom at time T4.

(E-4) Motions of the Pigment Particles

Having completed the resetting operation before starting the writingoperation, at time T0, the pigment particles 3 are all positioned on theside of pixels 104. At time T1, when the gradation voltage Vij isapplied to pixel electrodes 104, an electric field is applied in adirection from pixel electrodes 104 to the common electrode 201. Hencethe pigment particles 3 start to move, increasing the brightness Iij.

The electric field corresponding to the gradation voltage Vij is appliedover one scanning field from time T1 to time T4. Hence, during thisperiod, the pigment particles 3 continue moving to pixel electrodes 104.Namely, in the first embodiment, the gradation voltage Vij is applied ina certain period within one horizontal scanning, while in the fifthembodiment the gradation voltage is applied over a period of onescanning field. The amount of motion of the pigment particles 3 is, asexplained above, dependent on the electric field applied to thedispersal system and the duration thereof. In this embodiment, since theelectric field is applied over one scanning field for a long time, evena weak electric field can attain the brightness Iij desired. Thereforeit is possible to drive the data lines signal from X1 to Xn using lowvoltage based upon this embodiment.

(F) Sixth Embodiment

In this embodiment, it is possible to apply differential voltages toobtain desired gradations of an image displayed.

FIG. 31 is a timing chart showing the entire operation utilized inoperating the electrophoretic display. As shown therin, the image signalprocessing circuit 301A outputs the reset data Drest in the reset periodTr. In this period the pigment particles 3 are attracted to the pixelelectrodes 104 to enable their positions to be initialized.

The writing period Tw comprises a plurality of unit periods, consistingof a pair of applied period differential voltages Tdvf and no-biasperiod Tdbf. In gradation voltage applied period Tdvf, the gradationvoltage is applied to the pixel electrodes 104 based on the image data Doutputted from the image signal processing circuit 300A. The no-biassignal Cb remains inactive in this period and therefore the commonvoltage Vcom is not applied to the pixel electrodes 104.

However, in the no-bias period Tdbf, the image signal processing circuit300A supplies no data but the no-bias timing signal Cb becomes active,whereby the common voltage Vcom is applied to all of data lines 102.

As a result, the common voltage Vcom is applied to each of pixelelectrodes 104. That is, in this embodiment, the gradation voltage D isapplied within a particular scanning line period, and the differentialvoltage Vd is maintained until a scanned line is again selected. Afterthis, a common voltage Vcom is applied to the pixel electrodes 104 in aperiod in which the scanning line is selected next.

In the holding period Th, there is no electrostatic field between thepixel electrodes 104 and the common electrode 201, which enables to holdthe image displayed in the next previous writing period.

(F-2) Writing Operation

FIG. 32 is a timing chart of the electrophoretic display showing awriting operation. Depicted is Pij, located on an ith line and jthcolumn, but it is will be apparent to those skilled in the art thatother pixels can be described likewise. Provided that the gradation ofthe pixel Pij in the previous unit period is 10% and that in the presentunit period is 50%.

The voltage of the data line signal Xj which is supplied to the jth dataline 102 varies as a result of the scanning line period in thedifferential voltage applied period Tdvf as shown in FIG. 32. In theperiod of the ith scanning line, the data line signal Xj is equal to thedifferential voltage Vdij. At this time, since the scanning line signalYi becomes active (the H-level) the differential voltage Vdij is appliedto the pixel electrode 104. Thereby, at time T1, the voltage of thepixel electrode 104 shifts from the reset voltage Vrest to thedifferential voltage Vdij, with the result that the electrostatic fieldcorresponding to the display gradation to be displayed is applied to thedispersal system 1.

At time T2, when the scanning line signal Yi becomes inactive (theL-level), the TFT 103 of the pixel Pij shifts to OFF. However, sincesome charge is accumulated in the capacitor, the voltage of the pixelelectrode 104 remains subject to differential voltages Vdij.

In the period of the ith horizontal scanning in the no-bias period Tdbf,when the scanning signal Yi becomes active, the common voltage Vcom isapplied to the pixel electrode 104. Therefore the voltage of the pixelelectrode 104 coincides with a common voltage Vcom at time T4.

(G) Seventh Embodiment

(G-1) Display

In the electrophoretic device described in the second embodiment, thegradation voltage applied period Tv, the brake voltage applied periodTs, and the no-bias period Tb are set to constitute a period of onehorizontal scanning to migrate and brake the pigment particles 3.

Differently, in the seventh embodiment, a gradation voltage appliedperiod Tvf, the voltage applied period Tsf, and the no-bias period areset on a field-to-field basis.

The configuration of this electrophoretic device is similar to that ofthe third embodiment as shown in FIG. 3, except for the period in whichthe no-bias signal timing Cb is active.

(G-2) Whole Operation

FIG. 33 shows a timing chart of the whole operation in theelectrophoretic display. As shown therein, the image signal processingcircuit 301A output the reset data Drest in the reset period Tr. In thisperiod the pigment particles 3 are attracted to the pixel electrodes 104and their positions are initialized.

The writing period is composed, on a field-to-field basis, of thegradation voltage applied period Tvf, the brake voltage applied periodTsf and the no-bias period Tbf. In the gradation voltage applied periodTvf and the brake voltage applied period, the gradation voltage V andthe brake voltage Vs are applied to the pixel electrodes 104 based onthe outputted image data D and the brake voltage data Ds outputted fromthe image signal processing circuit 301A. However, since no-bias signalCb remains inactive in this period, the common voltage Vcom is notapplied to pixel electrodes 104.

While in the no-bias period Tbf, the image signal processing circuit300A supplies no data, the no-bias timing signal Cb becomes active,whereby the common voltage Vcom is applied to all data lines 102.Therefore common voltage Vcom is applied to each of pixel electrodes104. That is, in this embodiment, the gradation voltage V is appliedwithin a certain period during which line scanning is performed, andsubsequently a gradation voltage V is maintained until the scanning lineis again selected; after which brake voltage Vs is applied to pixelelectrodes 104. Subsequently, brake voltage V is maintained until thescanning line is again selected again, after which common voltage Vcomis applied to pixel electrodes 104 in a period during which the scanningline is selected next.

In the holding period Th, no electrostatic field exists between thepixel electrodes 104 and the common electrode 201, thereby enabling animage displayed to be held until the next writing period commences.

In the rewriting period, as in displaying of the first period, theseries of the processing which contains resetting, applying a gradationvoltage, applying a brake voltage, applying a common voltage (no-bias),and so on is carried out.

(G-3) Writing Operation

FIG. 34 is timing chart of the electrophoretic display in a writingoperation. Here will be described Pij which is on ith line and jthcolumn, but it will be apparent that other pixels can be describedlikewise. The voltage of the data line signal Xj which is supplied tothe jth dsta line 102 varies within the scanning line period of thegradation voltage applied period Tvf as shown in FIG. 34. In the periodof the ith scanning line, the data line signal Xj is equal to thegradation voltage Vij. At this time, since the scanning line signal Yibecomes active (the H-level) the gradation voltage Vij is applied to thepixel electrode 104. Thereby, at time T1, the voltage of the pixelelectrode 104 shifts from a reset voltage Vrest to a gradation voltageVij so that the electrostatic field according to the gradation to bedisplayed is applied to the dispersal system 1.

At time T2, when the scanning line signal Yi becomes inactive (theL-level), the TFT 103 of the pixel Pij shifts to OFF. However since somecharge is accumulated in the capacitor, the voltage of the pixelelectrode 104 remains the gradation voltages Vij. See previous.

In the period of the ith horizontal scanning of the brake voltageapplied period Tsf, when the scanning signal Yi becomes active, thebrake voltage Vsij according to the gradation voltage Vij is applied tothe pixel electrode 104. Hence the voltage of the pixel electrode 104 isequal to that of the brake voltage.

In another period of the ith horizontal scanning in the no-bias periodTbf, when the scanning signal Yi becomes active, the common voltage Vcomis applied to the pixel electrode 104. Therefore the voltage of thepixel electrode 104 coincides with the common voltage Vcom at time T4.

(G-4) Motions of Pigment Particles

Having completed the resetting operation before the writing operationstarts, at time T0, the pigment particles 3 are positioned at the sideof the pixels 104. At time T1, when the gradation voltage Vij is appliedto the pixel electrodes 104, an electrostatic field is applied in thedirection of from the pixel electrodes 104 to the common electrode 201.Hence the pigment particles 3 start to migrate, increasing brightnessIij.

In one horizontal scanning period of from T4 to T6, the brake voltageVsij is applied between the two electrodes. Since the brake voltage Vsijis negative relative to the common voltage Vcom, Coulomb force act inthe direction of from the common electrode 201 to the pixel electrode104, which is opposite to that of motions of the particles 3. Thiscauses the particles 3 to lose velocity and become stationary by timeT6. Additionally, in a period of from time T6 to time T7, a commonvoltage Vcom is applied to the pixel electrodes 104, thereby removing acharge accumulated between the electrodes. As a result, after time T7,ino electrostatic field is applied by even though TFT 103 is turned OFF.Consequently, the positions of the pigment particles 3 are set.

In the third embodiment, the gradation voltage Vij, the brake voltageVs, and the common voltage Vcom are applied within a defined periodconstituting one horizontal scanning; while in the seventh embodimentthe gradation voltage Vij and the brake voltage Vsij are applied over asingle scanning field period. In this embodiment, since theelectrostatic field is applied over the entire period of a scanningfield period, even a weak electrostatic field can attain a brightnessIij desired. Consequently, in this embodiment it is possible to drivethe data lines signal from X1 to Xn, using a low voltage.

(H) Eighth Embodiment

In the seventh embodiment, the gradation voltage is applied. However, itis also possible to apply a differential voltage.

(H-1) Operation

FIG. 35 is a timing chart of the whole operation in the electrophoreticdisplay. As shown, the image signal processing circuit 301B outputs thereset data Drest in the reset period Tr. In this period, the pigmentparticles 3 are attracted to the pixel electrodes 104 and theirpositions are initialized.

The writing period is composed, on a field-to-field basis, of thegradation voltage applied period Tdvf, the brake voltage applied periodTdsf and the no-bias period Tdbf. In the differential voltage appliedperiod Tdvf and the brake voltage applied period, the differentialvoltage Vd and brake voltage Vds are applied to the pixel electrodes 104based upon the outputted image data D and the brake voltage data Dsoutputted from the image signal processing circuit 301B. But the no-biassignal Cb remains inactive in that period hence the common voltage Vcomis not applied to the pixel electrodes 104.

While in the no-bias period Tdbf, the image signal processing circuit300A does not supply any data but the no-bias timing signal Cb becomesactive, so that the common voltage Vcom is applied to all the data lines102.

Therefore the common voltage Vcom is applied to each of the pixelelectrodes 104. That is, in this embodiment, the differential voltage Vdis applied in a preset period in which a particular scanning line isselected, with the differential voltage Vd being maintained during anext and different period in which the scanning line is again selected,after which the brake voltage Vds is applied to the pixel electrodes 104during a subsequent and different period in which the scanning line isagain selected, the brake voltage Vds then being maintained until thescanning line is once more selected in a next and different period,after which the common voltage Vcom is then applied to the pixelelectrodes 104 in a next and different period in which the scanning lineis once again selected. In the holding period Th, no electrostatic fieldexists between the pixel electrodes 104 and the common electrode 201,and thus image displayed in either a next or previous writing period canbe held.

In the rewriting period, as in a first time display, processing which iscarried out consists of applying a reset voltage, applying a gradientvoltage, applying a brake voltage, and applying a common voltage(no-bias).

(G-3) Writing Operation

FIG. 36 is timing chart of the electrophoretic display in the writingoperation. Here will be depicted about the pixel Pij which is on ithline and jth column, but it is obvious that other pixels can bedescribed likewise. Suppose a gradation of the pixel Pij in the nextprevious unit period is 10% and that in the present unit period is 50%,for instance.

The voltage of the data line signal Xj, which is supplied to the jthdata line 102, equals to the differential voltage Vdij in the ithhorizontal scanning in the differential voltage applied period Tdvf asshown in FIG. 36. At this time, since the scanning line signal Yibecomes active (the H-level), the differential voltage Vdij is appliedto the pixel electrode 104. Thereby, at time T1, the voltage of thepixel electrode 104 shifts from the reset voltage Vrest to thedifferential voltage Vdij so that the electrostatic field according tothe gradation to be displayed is applied to the dispersal system 1.

At time T2, when the scanning line signal Yi becomes inactive (theL-level), the TFT 103 of the pixel Pij shifts to OFF. However, sincesome charge is accumulated in the capacitor, the voltage of the pixelelectrode 104 remains in the form of the differential voltages Vdij.

In the period of the ith horizontal scanning of the brake voltageapplied period Tdsf, when the scanning signal Yi becomes active, thebrake voltage Vdsij according to the differential voltage Vdij isapplied to the pixel electrode 104. Hence the voltage of the pixelelectrode 104 is equal to that of the brake voltage.

In another period of the ith horizontal scanning in the no-bias periodTdbf, when the scanning signal Yi becomes active, the common voltageVcom is applied to the pixel electrode 104. Therefore the voltage of thepixel electrode 104 coincides with the common voltage Vcom at time T4.

(I) Applications

So far, several embodiments have been described, However, it is to beunderstood by those skilled in the art that this invention is notrestricted in these embodiments, and various applications and variationsare possible.

Following are some variations.

(I-1) Displaying of Animation

In the above embodiments, the process of displaying an image consists offirst resetting then writing, subsequently holding, and then rewritingif necessary.

As a result, the electrophoretic displays in those embodiments aresuitable for displaying a static image. However it is possible todisplay an animation by making the reset period Tr as well as byrepeating rewriting periodically. In displaying an animation, it ispreferable that the velocity of the pigment particles 3 should be high.This means that small fluid resistance is more suitable. In such asituation, the pigment particles 3 are likely to continue to move due totheir inertia after removal of the electrostatic field. Therefore it ispreferable to brake the particles 3 by applying the brake voltage asdescribed above.

(I-2) Refreshing

It is preferable that the specific gravity of the dielectric fluid 2 andthat of the pigment particles 3 which comprise the dispersal system 1 beequal. However, it is difficult to achieve complete parity of therespective specific gravities, due to restrictions of materials employedand variations therein. In such a case, when the dispersal system 1 isleft in stasis for a long time once an image is displayed, the pigmentparticles 3 sink down or float up due to gravitational effect. In orderto overcome this problem, it is preferable for a timer apparatus to beset in the timing generator 400 to rewrite the same image for a certainperiod. The timer apparatus 410 has a timer part 411 and a comparisonpart 412. The timer generates duration data Dt measuring time, in whichthe value of the duration data Dt is reset to ‘0’ when either a writingstart signal Ws which designates an ordinary writing, or a rewritingsignal Ws′ becomes active. The comparison part 412 compares the durationdata Dt with the predetermined reference time data Dref which designatesthe refresh period and, if they coincide, generates the rewriting signalWs′ which is active during a preset period.

FIG. 38 is a timing chart of the timer apparatus 410. As shown, when thewriting signal Ws becomes active, the duration data Dt of the timingpart 411 is reset and measurement starts. When predetermined refreshperiod has passed, the duration data Dt and the reference time data Drefcoincides, so that the rewriting signal Ws′ becomes active. Themeasurement of refreshing period starts when the writing signal Wsbecomes active, or the rewriting signal Ws′ is active once the refreshperiod passes.

By executing the rewriting operation (but the same image) described inthe above embodiments, by using the rewriting signal Ws′ which isgenerated to function as a trigger, a displayed image is refreshed.

(I-3) Electronic Devices

Electronic devices attached to the electrophoretic display describedabove are described as follows:

(1) Electronic books

FIG. 39 is a perspective view showing an electronic book. Thiselectronic book 1000 is provided with an electrophoretic display panel1001, a power switch 1002, a first button 1003, a second button 1004,and a CD-ROM slot 1005, as shown.

When a user activates the power switch 1002 and then loads a CD-ROM inthe CD-ROM drive 1005, contents of the CD-ROM are read out and theirmenus displayed on the electrophoretic display panel 1001. If the useroperates the first and second buttons 1003 and 1004 to select a desiredbook, the first page of the selected book is displayed on the panel1001. To scroll down pages, the second button 1004 is pressed, and toscroll up pages, the first button 1003 is pressed.

In this electronic book 1000, if a page of the book is once displayed onthe panel screen, the displayed screen will be updated only when thefirst or second button 1003 or 1004 is pressed. This is because, asstated previously, the pigment particles 3 will migrate only in when anelectrostatic field is applied. In other words, to hold the same screendisplay, it is unnecessary to reapply any voltage. Only during a periodfor updating displayed images, is it necessary to feed power to thedriving circuits to drive the electrophoretic display panel 1001. Thus,in comparison to liquid crystal displays, power consumption is greatlyreduced.

Further, images are displayed on the panel 1001 by way of the pigmentparticles 3 thus preventing any impression of artificial brightness, andproviding display characteristics in the electronic book 1000 which areclose to those provided or in printed matter. This proximity of displaycharacteristics of the electronic book to printed matter limitseyestrain and makes it possible for the electronic book to be read forextended periods of time.

(2) Personal Computer

A portable, note-book typecomputer in which the electrophoretic displayis applied will now be exemplified. FIG. 40 is an external perspectiveview showing such a computer. As shown, the computer 1200 has a mainunit 1204 on which a keyboard 1202 is mounted and an electrophoreticdisplay panel 1206. On the panel 1206, images are displayed via pigmentparticles 3. Hence, it is unnecessary to mount a back light, which isrequired in transmission type and semi-transmission type of liquidcrystal displays, thereby imparting to the computer 1200 a lower weightand smaller size, in addition to greatly decreased power consumption.

(3) Mobile Phone

A mobile phone into which is incorporated the electrophoretic displaypanel will now be exemplified. FIG. 41 is a an external perspective viewof a portable phone. As shown, a portable phone 1300 is provided with aplurality of operation buttons 1302, an ear piece 1304, a mouth piece1306, and an electrophoretic display panel 1308.

In liquid crystal displays, a polarizing plate is a requisite componentfor enabling a display screen to be darkened. In the electrophoreticdisplay panel 1308, however, a polarizing plate is not required. Hencethe portable phone 1300 is equipped with a bright and readily viewablescreen.

Electronic devices other than those shown in FIGS. 39 to 41 include a TVmonitor, outdoor advertising board, traffic sign, view-finder type ormonitor-direct-viewing type display of a vidoe tape recorder, carnavigation device, pager, electronic note pad, electronic calculator,word processor, work station, TV telephone, POS terminal, devices havinga touch panel, and others. Thus, the electrophoretic display panelaccording to each of the foregoing embodiments can be applied for usewith such devices. Alternatively, an electro-optical apparatuses havingsuch electrophoretic display panel can also be applied to such devices.

1. A method for driving an electrophoretic display, the displaycomprising: a plurality of data lines; a plurality of scanning lines,each of which intersects said data lines; a common electrode; aplurality of pixel electrodes, with one of said plurality of pixelelectrodes being provided at one of each of said intersections of saiddata lines and said scanning lines, each of said pixel electrodes beingprovided in opposing spaced relation to said common electrode; aplurality of dispersal systems including a fluid in which pigmentparticles are suspended, with each of said dispersal systems beingprovided between said common electrode and one of said pixel electrodes;and a plurality of switching elements, with one of each of saidswitching elements being provided at a corresponding one of each of saidintersections of said data lines and said scanning lines, with an on/offcontrol terminal being connected to one of said scanning lines passingthrough one of said intersections; and with one of said data linespassing through one of said intersections, being connected to one ofsaid pixel electrodes provided at each of one said intersections; andthe method comprising: controlling an image displayed by employing saidscanning lines and said data lines, each of said voltages being appliedwithin a set period of a single scanning field, in which all of saidscanning lines are once scanned; and within said period of a singlescanning field, applying a common voltage to a said pixel electrode;selecting a scanning line sequentially; applying a voltage to a selectedscanning line, to turn on all switching elements connected to saidselected scanning lines; applying a plurality of pixel voltages to aplurality of said data lines for a set time, to generate electrostaticfields to cause said pigment particles to migrate to positionscorresponding to desired gradations of an image displayed; and afterapplying said pixel voltages to said data lines, applying a plurality ofbrake voltages to said data lines for a set time, to createelectrostatic fields in each of said dispersal systems, each of saidbrake voltages determined based on fluid resistance of said pigmentparticles and a respective one of said desired gradations; applying avoltage to said sequentially selected scanning lines, to turn off all ofsaid switching elements connected to said sequentially selected scanningline.
 2. The method of claim 1, wherein resetting operation is performedduring a period of said scanning field and writing operation isperformed during a period of a different scanning field, said resettingand writing operations performed alternately, and the method furthercomprising the steps of: in said period for said resetting operation,applying a reset voltage to said plurality of data lines, to create anelectrostatic field in each of said dispersal systems, to initializesaid pigment particles; and in said period for said rewriting operation,applying to said selected data lines a plurality of voltagescorresponding to said desired gradations.
 3. The method of claim 2,wherein when a displayed image is switched, said pixel voltage and saidreset voltage are applied to only those pixel electrodes correspondingto pixels, the gradation of which pixels change following switching ofan image displayed.
 4. The method of claim 3, wherein: a plurality ofsaid scanning lines are selected simultaneously; and said reset voltageis applied to a plurality of said data lines, so that said reset voltageis applied simultaneously to said plurality of pixel electrodes toinitialize said pigment particles.
 5. The method of claim 1, wherein:resetting operation is performed during a period of a scanning field andwriting operation is performed during a period of next and differentscanning field, in said period for said resetting operation, applyingsaid reset voltage is applied to said plurality of pixel electrodes, toinitialize said pigment particles; and in said period for said writingoperation, a plurality of differential voltages are applied to said datalines, each of which differential voltages corresponds to a differencebetween a voltage corresponding to a gradation displayed in a previouswriting operation, and a gradation to be displayed.
 6. The method ofclaim 1, wherein: the electrophoretic display includes a table forstoring brake voltage data representing values of said brake voltages;and said brake voltage data is retrieved from said table based on imagedata used for switching a displayed image.
 7. The method of claim 1,wherein: the display further comprises a timer apparatus; and adisplayed image is refreshed at a predetermined period of time.
 8. Adrive circuit for driving an electrophoretic display, the displaycomprising: a plurality of data lines; a plurality of scanning lines,each of which intersects said data lines; a common electrode; aplurality of pixel electrodes, with one of said plurality of pixelelectrodes being provided at one of each of said intersections of saiddata lines and said scanning lines, each of said pixel electrodes beingprovided in opposing spaced relation to said common electrode; aplurality of dispersal systems including a fluid in which pigmentparticles are suspended, with each of said dispersal systems beingprovided between said common electrode and one of said pixel electrodes;and a plurality of switching elements, with one of each of saidswitching elements being provided at a corresponding one of each of saidintersections of said data lines and said scanning lines, with an on/offcontrol terminal being connected to one of said scanning lines passingthrough one of said intersections; and with one of said data linespassing through one of said intersections, being connected to one ofsaid pixel electrodes provided at each of one said intersections; thedrive circuit comprising: an applying unit for applying said commonvoltage to said common electrode; a scanning drive unit for selecting ascanning line sequentially, applying a voltage to a selected scanningline, so as to turn on all of said switching elements which areconnected to said sequentially selected scanning line during a certainperiod of time, and applying a voltage to said selected scanning line,so as to turn off all of said switching elements; and a data line driveunit for applying said common voltage to data lines, applying aplurality of pixel voltages to said data lines during a certain periodof time, to migrate said pigment particles to positions corresponding todesired gradations, applying a plurality of brake voltages for brakingsaid pigment particles to said data lines, each of said plurality brakevoltages determined based on fluid resistance of said pigment particlesand respective one of said desired gradations, and after saidapplication of said brake voltages applying said common voltage to saiddata lines, said applications of said gradation voltages and brakevoltages performed during a period in which a single scanning line isselected for applying a voltage to turn on all of said switchingelements.
 9. The drive circuit of claim 8, wherein: resetting operationis performed during a period of a scanning field and writing operationis performed during a period of a different scanning field, saidresetting and writing operations performed alternately; in said periodfor said resetting operation, said drive circuit applies a reset voltageto said plurality of data lines, to create an electrostatic field ineach of said dispersal systems, to initialize said pigment particles;and in said period for said rewriting operation, said drive circuitapplies to said selected data lines a plurality of voltagescorresponding to said desired gradations.
 10. The drive circuit of claim8, wherein: resetting operation is performed during a period of ascanning field and writing operation is performed during a period ofnext and different scanning field, in said period for said resettingoperation, said drive circuit applies said reset voltage to saidplurality of pixel electrodes, to initialize said pigment particles; andin said period for said writing operation, said drive circuit applies aplurality of differential voltages to said data lines, each of whichdifferential voltages corresponds to a difference between a voltagecorresponding to a gradation displayed in a previous writing operation,and a gradation to be displayed.
 11. The method of claim 8, wherein: atable for storing brake voltage data representing values of said brakevoltages is provided with the display; and said brake voltage data isretrieved from said table based on image data used for switching adisplayed image.
 12. The method of claim 8, wherein: the display furthercomprises a timer apparatus; and a displayed image is refreshed at apredetermined period of time.
 13. An electrophoretic display,comprising: a plurality of data lines; a plurality of scanning lines,each of which intersects said data lines; a common electrode; aplurality of pixel electrodes, with one of said plurality of pixelelectrodes being provided at one of each of said intersections of saiddata lines and said scanning lines, each of said pixel electrodes beingprovided in opposing spaced relation to said common electrode; aplurality of dispersal systems including a fluid in which pigmentparticles are suspended, with each of said dispersal systems beingprovided between said common electrode and one of said pixel electrodes;and a display panel that includes a plurality of switching elements,with one of each of said switching elements being provided at acorresponding one of each of said intersections of said data lines andsaid scanning lines, with an on/off control terminal being connected toone of said scanning lines passing through one of said intersections;with one of said data lines passing through one of said intersections,being connected to one of said pixel electrodes provided at each of onesaid intersections; an applying unit for applying said common voltage tosaid common electrode; a scanning drive unit for selecting a scanningline sequentially, applying a voltage to a selected scanning line, so asto turn on all of said switching elements which are connected to saidsequentially selected scanning line during a certain period of time, andapplying a voltage to said selected scanning line, so as to turn off allof said switching elements; and a data line drive unit for applying saidcommon voltage to data lines, applying a plurality of pixel voltages tosaid data lines during a certain period of time, to migrate said pigmentparticles to positions corresponding to desired gradations, applying aplurality of brake voltages for braking said pigment particles to saiddata lines, each of said brake voltages determined based on fluidresistance of said pigment particles and respective one of said desiredgradations, and after said application of said brake voltages applyingsaid common voltage to said data lines, said applications of saidgradation voltages and brake voltages performed during a period in whicha single scanning line is selected for applying a voltage to turn on allof said switching elements.
 14. The electrophoretic display of claim 13,wherein said pigment particles reflect a certain color being displayedin said pixels and said fluid absorbs said color.
 15. Theelectrophoretic display of claim 13, each of said plurality of saiddispersal systems includes three subsets of dispersal systems, in eachof the subsets red, blue, and green particles being contained, so as todisplay a colored image.
 16. The electrophoretic display of claim 13,wherein said pigment particles are provided with differing properties.17. An electronic device with which an electrophoretic display provided,the electrophoretic display, comprising: a plurality of data lines; aplurality of scanning lines, each of which intersects said data lines; acommon electrode; a plurality of pixel electrodes, with one of saidplurality of pixel electrodes being provided at one of each of saidintersections of said data lines and said scanning lines, each of saidpixel electrodes being provided in opposing spaced relation to saidcommon electrode; a plurality of dispersal systems including a fluid inwhich pigment particles are suspended, with each of said dispersalsystems being provided between said common electrode and one of saidpixel electrodes; a display panel that includes a plurality of switchingelements, with one of each of said switching elements being provided ata corresponding one of each of said intersections of said data lines andsaid scanning lines, with an on/off control terminal being connected toone of said scanning lines passing through one of said intersections;with one of said data lines passing through one of said intersections,being connected to one of said pixel electrodes provided at each of onesaid intersections; an applying unit for applying said common voltage tosaid common electrode; a scanning drive unit for selecting a scanningline sequentially, applying a voltage to a selected scanning line, so asto turn on all of said switching elements which are connected to saidsequentially selected scanning line during a certain period of time, andapplying a voltage to said selected scanning line, so as to turn off allof said switching elements; and a data line drive unit for applying saidcommon voltage to data lines, applying a plurality of pixel voltages tosaid data lines during a certain period of time, to migrate said pigmentparticles to positions corresponding to desired gradations, applying abrake voltage for braking said pigment particles to said data lines,said brake voltages determined based on fluid resistance of said pigmentparticles and said desired gradations, and after said application ofsaid brake voltages applying said common voltage to said data lines,said applications of said gradation voltages and brake voltagesperformed during a period in which a single scanning line is selectedfor applying a voltage to turn on all of said switching elements.